Question

1.圆柱的高是12cm,一个圆锥的底面半径是圆柱底面半径的2分之3,体积是它体积的4分之5,圆锥的高是（）.2.一个圆柱

Answer 1

R锥=2/3R柱,V锥=4/5V柱,V锥=1/3Sh=1/3*πR锥^2*h=4/27πR柱^2h锥,V柱=Sh=πR柱^2*12

4/27h锥=4/5*12,得h=64.8.

V柱-V锥=1/4V锥,V锥=4/5V柱,V柱=S柱h柱,V锥=1/3S锥h锥=4/5S柱h柱,h锥=1/6h柱,1/18S锥h柱=4/5S柱h柱,S柱/S锥=5/4/18=5/72